QUANTITATION OF THE β‐ELIMINATION REACTION AS USED ON GLYCOPROTEINS

Abstract

The carbohydrate side chains of mucus-type glycoproteins are O-glycosidic bonds between N-acetylgalactosamine to the hydroxyl groups of serine and threonine in the protein core. The alkaline catalyzed .beta.-elimination reaction, in the presence of sodium borohydride, is used for determining the number of side chains. A study of the quantitativeness of the alkaline borohydride procedure is presented, using 4 parameters: the loss of seryl and threonyl residues, the formation of alanine and 2-aminobutanoic acid, the decrease in N-acetylhexosamine and the recovery of the amino sugar alcohols. Bovine, ovine and porcine submandibular glycoproteins were studied. Evidence is presented for the existence of N-acetylglucosamine involvement in O-glycosidic linkages to serine and threonine. Results for the relative rates of .beta.-elimination indicate that serine-linked glycosides are released more rapidly than threonine-linked glycosides.